自组装银膜增强8-羟基喹啉铝(Alq_3)光致发光的实验和理论研究

Experimental and theoretical study of tris-(8-hydroxyquinoline) aluminum (Alq_3) photoluminescence enhanced by self-assembled silver films

实验和理论研究了不同自组装密度的银纳米颗粒膜对8-羟基喹啉铝(Alq_3)光致发光的影响,结果表明:Alq_3光致发光的表观增强和发射增强因子与银纳米颗粒膜密度呈正相关关系,最大值约为3.2和13;理论计算表明银纳米颗粒膜对Alq_3光致发光的量子效率和发射的最大增强因子约为1.4和15,对比实验和理论结果,金属纳米颗粒膜的近场场强增强是导致Alq3光致发光发射强度增强的主要因素,且Alq_3光致发光效率与Alq_3相对银纳米颗粒的分布和"热点"区域面积覆盖率有关。

Alq3 photoluminescences （PL） enhanced by self-assembled silver films are investigated experimentally and theoret-ically. The experimental results show that both the apparent enhancement factor （AEF） and the emission enhancement factor （EEF） of Alq3 PL increase with the increase of density of average 70 nm diameter silver nanoparticles on the substrate. The maxima of AEF and EEF are about 3.2 and 13, respectively. Based on the optical antenna theory, the theoretical maxima of both quantum efficiency enhancement factor and EEF of Alq3 PL are about 1.4 and 15, respectively. By comparing of the experimental results with the theoretical results, we can conclude that the near-field enhancement of silver nanoparticles makes a major contribution to Alq3 PL emission enhancement, and the emission enhancement is dependent on the Alq3-silver nanoparticle distance and the area coverage ratio of silver nanoparticles to substrate.